Thin-film magnetic head and method of manufacturing same

ABSTRACT

A recording head has a bottom pole layer and a top pole layer that include pole portions, and a recording gap layer placed between the pole portions. The recording head further has a thin-film coil placed between the bottom and top pole layers, the coil being insulated from the pole layers. The bottom pole layer includes a first portion and a second portion. The first portion is located in a region facing toward the thin-film coil, an insulating layer being placed between the bottom pole layer and the coil. The second portion is connected to a surface of the first portion facing toward the thin-film coil. The second portion forms the pole portion and defines a throat height. The thin-film coil is located on a side of the second portion. Throat height TH is greater than MR height MR-H.

This is a Division of application Ser. No. 09/592,297 filed Jun. 12,2000. Now U.S. Pat No. 6,826,012. The entire disclosure of the priorapplication is hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a composite thin-film magnetic headcomprising a reproducing head and a recording head and to a method ofmanufacturing such a thin-film magnetic head.

2. Description of the Related Art

Performance improvements in thin-film magnetic heads have been sought assurface recording density of hard disk drives has increased. Suchthin-film magnetic heads include composite thin-film magnetic heads thathave been widely used. A composite head is made of a layered structureincluding a recording head having an induction-type magnetic transducerfor writing and a reproducing head having a magnetoresistive (MR)element for reading.

It is required to increase the track density on a magnetic recordingmedium in order to increase recording density among the performancecharacteristics of a recording head. To achieve this, it is required toimplement a recording head of a narrow track structure wherein a trackwidth, that is, the width of top and bottom poles sandwiching therecording gap layer on a side of the air bearing surface, is reduceddown to microns or the submicron order. Semiconductor process techniquesare utilized to implement such a structure.

Reference is now made to FIG. 23A to FIG. 26A and FIG. 23B to FIG. 26Bto describe an example of a method of manufacturing a compositethin-film magnetic head as an example of a related-art method ofmanufacturing a thin-film magnetic head. FIG. 23A to FIG. 26A are crosssections each orthogonal to an air bearing surface of the thin-filmmagnetic head. FIG. 23B to FIG. 26B are cross sections of a pole portionof the head each parallel to the air bearing surface.

In the manufacturing method, as shown in FIG. 23A and FIG. 23B, aninsulating layer 102 made of alumina (Al₂O₃), for example, having athickness of about 5 to 10 μm is deposited on a substrate 101 made ofaluminum oxide and titanium carbide (Al₂O₃—TiC), for example. On theinsulating layer 102 a bottom shield layer 103 made of a magneticmaterial is formed for making a reproducing head.

Next, on the bottom shield layer 103, alumina, for example, is depositedto a thickness of 100 to 200 nm through sputtering to form a bottomshield gap film 104 as an insulating layer. On the bottom shield gapfilm 104 an MR element 105 for reproduction having a thickness of tensof nanometers is formed. Next, a pair of electrode layers 106 are formedon the bottom shield gap film 104. The electrode layers 106 areelectrically connected to the MR element 105.

Next, a top shield gap film 107 is formed as an insulating layer on thebottom shield gap film 104 and the MR element 105. The MR element 105 isembedded in the shield gap films 104 and 107.

Next, on the top shield gap film 107, atop-shield-layer-cum-bottom-pole-layer (called a bottom pole layer inthe following description) 108 having a thickness of about 3 μm isformed. The bottom pole layer 108 is made of a magnetic material andused for both a reproducing head and a recording head.

Next, as shown in FIG. 24A and FIG. 24B, on the bottom pole layer 108, arecording gap layer 109 made of an insulating film such as an aluminafilm whose thickness is 0.2 μm is formed. Next, a portion of therecording gap layer 109 is etched to form a contact hole 109 a to make amagnetic path. On the recording gap layer 109 in the pole portion, a toppole tip 110 made of a magnetic material and having a thickness of 0.5to 1.0 μm is formed for the recording head. At the same time, a magneticlayer 119 made of a magnetic material is formed for making the magneticpath in the contact hole 109 a for making the magnetic path.

Next, as shown in FIG. 25A and FIG. 25B, the recording gap layer 109 andthe bottom pole layer 108 are etched through ion milling, using the toppole tip 110 as a mask. As shown in FIG. 25B, the structure is called atrim structure wherein the sidewalls of the top pole (the top pole tip110), the recording gap layer 109, and a part of the bottom pole layer108 are formed vertically in a self-aligned manner.

Next, an insulating layer 111 made of an alumina film, for example, andhaving a thickness of about 3 μm is formed on the entire surface. Theinsulating layer 111 is then polished to the surfaces of the top poletip 110 and the magnetic layer 119 and flattened.

Next, on the flattened insulating layer 111, a first layer 112 of athin-film coil is made of copper (Cu), for example, for theinduction-type recording head. Next, a photoresist layer 113 is formedinto a specific shape on the insulating layer 111 and the first layer112. Heat treatment is then performed at a specific temperature toflatten the surface of the photoresist layer 113. On the photoresistlayer 113, a second layer 114 of the thin-film coil is then formed.Next, a photoresist layer 115 is formed into a specific shape on thephotoresist layer 113 and the second layer 114. Heat treatment is thenperformed at a specific temperature to flatten the surface of thephotoresist layer 115.

Next, as shown in FIG. 26A and FIG. 26B, a top pole layer 116 is formedfor the recording head on the top pole tip 110, the photoresist layers113 and 115, and the magnetic layer 119. The top pole layer 116 is madeof a magnetic material such as Permalloy. Next, an overcoat layer 117 ofalumina, for example, is formed to cover the top pole layer 116.Finally, lapping of the slider is performed to form the air bearingsurface 118 of the thin-film magnetic head including the recording headand the reproducing head. The thin-film magnetic head is thus completed.

FIG. 27 is a top view of the thin-film magnetic head shown in FIG. 26Aand FIG. 26B. The overcoat layer 117 and the other insulating layers andinsulating films are omitted in FIG. 27.

In FIG. 26A, ‘TH’ indicates the throat height and ‘MR-H’ indicates theMR height. The throat height is the length (height) of pole portions,that is, portions of magnetic pole layers facing each other with arecording gap layer in between, the length between theair-bearing-surface-side end and the other end. The MR height is thelength (height) between the air-bearing-surface-side end of the MRelement and the other end. In FIG. 26B, ‘P2W’ indicates the pole width,that is, the track width of the recording head (hereinafter called therecording track width). In addition to the factors such as the throatheight and the MR height, the apex angle as indicated with θ in FIG. 26Ais one of the factors that determine the performance of a thin-filmmagnetic head. The apex is a hill-like raised portion of the coilcovered with the photoresist layers 113 and 115. The apex angle is theangle formed between the top surface of the insulating layer 111 and thestraight line drawn through the edges of the pole-side lateral walls ofthe apex.

In order to improve the performance of the thin-film magnetic head, itis important to precisely form throat height TH, MR height MR-H, apexangle θ, and track width P2W as shown in FIG. 26A and FIG. 26B.

To achieve high surface recording density, that is, to fabricate arecording head with a narrow track structure, it has been particularlyrequired that track width P2W fall within the submicron order of 1.0 μmor less. It is therefore required to process the top pole of thesubmicron order through semiconductor process techniques.

A problem is that it is difficult to form the top pole layer of smalldimensions on the apex.

As disclosed in Published Unexamined Japanese Patent Application Hei7-262519 (1995), for example, frame plating may be used as a method forfabricating the top pole layer. In this case, a thin electrode film madeof Permalloy, for example, is formed by sputtering, for example, tofully cover the apex. Next, a photoresist is applied to the top of theelectrode film and patterned through a photolithography process to forma frame to be used for plating. The top pole layer is then formed byplating through the use of the electrode film previously formed as aseed layer.

However, there is a difference in height between the apex and the otherpart, such as 7 to 10 μm or more. The photoresist whose thickness is 3to 4 μm is applied to cover the apex. If the photoresist thickness isrequired to be at least 3 μm over the apex, a photoresist film having athickness of 8 to 10 μm or more, for example, is formed below the apexsince the fluid photoresist goes downward.

To implement a recording track width of the submicron order as describedabove, it is required to form a frame pattern having a width of thesubmicron order through the use of a photoresist film. Therefore, it isrequired to form a fine pattern of the submicron order on top of theapex through the use of a photoresist film having a thickness of 8 to 10μm or more. However, it is extremely difficult to form a photoresistpattern having such a thickness into a reduced pattern width, due torestrictions in a manufacturing process.

Furthermore, rays of light used for exposure of photolithography arereflected off the base electrode film as the seed layer. The photoresistis exposed to the reflected rays as well and the photoresist pattern maygo out of shape. It is therefore impossible to obtain a sharp andprecise photoresist pattern.

In the region on the slope of the apex, in particular, the raysreflected off the bottom electrode film include not only verticalreflected rays but also rays in slanting directions and rays in lateraldirections from the slope of the apex. As a result, the photoresist isexposed to those reflected rays of light and the photoresist patternmore greatly goes out of shape.

With regard to the track width, it is required that the amount oflapping the slider will not affect the track width.

Therefore, when the top pole layer is formed on the apex, some means isrequired for reducing the effect on the track width of the raysreflected off the bottom electrode film during exposure of thephotolithography process.

For example, the top pole layer of a prior-art thin film magnetic headhas the shape including a portion having a width equal to the trackwidth. This portion is located between the air bearing surface and apoint at a distance of only 3 to 5 μm, for example, from the zero throatheight position (the position of an end of the pole portion opposite tothe air bearing surface) toward the apex. A portion of the top polelayer next to the portion having a width equal to the track width has awidth extending toward the coil at an obtuse angle of 30 or 45 degrees.

However, if the top pole layer has the shape as described above, amagnetic flux is saturated near the zero throat height position and itis impossible to efficiently utilize the magnetomotive force generatedby the coil for writing. As a result, the value indicating an overwriteproperty is reduced down to about 10 to 20 dB, for example. Theoverwrite property is a parameter indicating one of characteristics whendata is written over existing data on a recording medium. It istherefore difficult to obtain a sufficient overwrite property.

In addition, if the top pole layer has the shape as described above, aportion of the top pole layer whose width starts to extend is located onthe slope of the apex. However, if the top pole layer has such a shapeand is located in such a manner, the photoresist pattern is particularlysusceptible to the rays reflected off the bottom electrode film. It istherefore difficult to precisely control the track width.

As thus described, the problem of the prior art is that it is difficultto precisely control the track width if the track width of the submicronorder is required and that a magnetic flux is likely to saturate nearthe zero throat height position.

In order to implement a thin-film magnetic head that achieves surfacerecording density of 10 to 40 gigabits per square inches, for example,or a thin-film magnetic head that performs recording in a good conditionat a frequency as high as 300 to 600 MHz, for example, it isparticularly important to form a reduced track width with uniformity andto utilize the magnetomotive force generated by the coil with efficiencyfor writing. It is therefore strongly required to solve theabove-mentioned problems.

To overcome the problems thus described, a method has been taken, asshown in the foregoing related-art manufacturing steps illustrated inFIG. 24A to FIG. 26A and FIG. 24B to FIG. 26B. In this method, a trackwidth of 1.0 μm or less is formed through the use of the top pole tip110 effective for making a narrow track of the recording head. The toppole layer 116 to be a yoke portion connected to the top pole tip 110 isthen fabricated (as disclosed in Published Unexamined Japanese PatentApplication Sho 62-245509 [1987] and Published Unexamined JapanesePatent Application Sho 60-10409 [1985]). That is, the ordinary top polelayer is divided into the top pole tip 110 and the top pole layer 116 tobe the yoke portion in this method. As a result, it is possible that thetop pole tip 110 that defines the track width is formed into smalldimensions to some degree on the flat top surface of the recording gaplayer 109.

However, the following problems are still found in the thin-filmmagnetic head having a structure as shown in FIG. 26A and FIG. 26B.

In the thin-film magnetic head shown in FIG. 26A and FIG. 26B, therecording track width is defined by the top pole tip 110. Therefore, itis not necessary that the top pole layer 116 is processed intodimensions as small as those of the top pole tip 110. However, if therecording track width is extremely reduced, that is, down to 0.5 μm orless, in particular, processing accuracy for achieving thesubmicron-order width is required for the top pole layer 116, too.However, the top pole layer 116 is formed on top of the apex in the headshown in FIG. 26A and FIG. 26B. Therefore, it is difficult to reduce thetop pole layer 116 in size, due to the reason described above. Inaddition, the top pole layer 116 is required to be greater than the toppole tip 110 in width since the top pole layer 116 is required to bemagnetically connected to the top pole tip 110 smaller in width. Becauseof these reasons, the top pole layer 116 is greater than the top poletip 110 in width in this thin-film magnetic head. In addition, the endface of the top pole layer 116 is exposed from the air bearing surface.As a result, writing may be performed by the thin-film magnetic head ona side of the top pole layer 116, too, and so-called ‘side write’ mayresult, that is, data is written in a region of a recording medium wheredata is not supposed to be written. Such a problem more frequentlyresults when the coil is two-layer or three-layer to improve theperformance of the recording head and the apex is thereby increased inheight, compared to the case where the coil is one-layer.

In the thin-film magnetic head shown in FIG. 26A and FIG. 26B, therecording track width and the throat height are defined by the top poletip 110. Therefore, if the recording track width is extremely reduced,that is, down to 0.5 μm or less, in particular, the size of the top poletip 110 is thus extremely reduced. As a result, pattern edges may berounded and it is difficult to form the top pole tip 110 with accuracy.Therefore, the thin-film magnetic head having the structure as shown inFIG. 26A and FIG. 26B has a problem that it is difficult to preciselydefine the recording track width and the throat height if the recordingtrack width is extremely reduced.

In the thin-film magnetic head shown in FIG. 26A and FIG. 26B, thecross-sectional area of the magnetic path abruptly decreases in aportion where the top pole layer 116 is in contact with the top pole tip110. Consequently, the magnetic flux is saturated in this portion, andit is impossible to efficiently utilize the magnetomotive forcegenerated by the layers 112 and 114 of the thin-film coil for recording.

Furthermore, it is difficult to reduce the magnetic path (yoke) lengthof a prior-art magnetic head. That is, if the coil pitch is reduced, ahead with a reduced yoke length is achieved and a recording head havingan excellent high frequency characteristic is achieved, in particular.However, if the coil pitch is reduced to the limit, the distance betweenthe zero throat height position (the position of theair-bearing-surface-side end of the insulating layer that defines thethroat height) and the outermost end of the coil is a major factor thatprevents a reduction in yoke length. Since the yoke length of atwo-layer coil can be shorter than that of a single-layer coil, atwo-layer coil is adopted to many of recording heads for high frequencyapplication. However, in the prior-art magnetic head, a photoresist filmhaving a thickness of about 2 μm is formed to provide an insulating filmbetween coil layers after a first layer is formed. Consequently, a smalland rounded apex is formed at the outermost end of the first layer ofthe coil. A second layer of the coil is then formed on the apex. Thesecond layer is required to be formed on a flat portion since it isimpossible to etch the seed layer of the coil in the sloped portion ofthe apex, and the coil is thereby shorted.

Therefore, if the total coil thickness is 2 to 3 μm, the thickness ofthe insulating film between the layers of the coil is 2 μm, and the apexangle is 45 to 55 degrees, for example, the yoke length is required tobe 6 to 8 μm which is twice as long as the distance between theoutermost end of the coil and the neighborhood of the zero throat heightposition, that is, 3 to 4 μm (the distance between the innermost end ofthe coil and the portion where the top and bottom pole layers are incontact with each other is required to be 3 to 4 μm, too), in additionto the length of the portion corresponding to the coil. This length ofthe portion other than the portion corresponding to the coil is one ofthe factors that prevent a reduction in yoke length.

Assuming that a two-layer eleven-turn coil in which the line width is1.2 μm and the space is 0.8 μm is fabricated, for example, the portionof the yoke length corresponding to the first layer 112 of the coil is11.2 μm, if the first layer is made up of six turns and the second layeris made up of 5 turns, as shown in FIG. 26A and FIG. 26B. In addition tothis length, the total of 6 to 8 μm, that is, the distance between eachof the outermost and innermost ends of the first layer 112 of the coiland each of ends of the photoresist layer 113 for insulating the firstlayer 112, is required for the yoke length. Therefore, the yoke lengthis 17.5 to 19.5 μm. In the present patent application, the yoke lengthis the length of a portion of the pole layer except the pole portion andthe contact portions, as indicated with L₀ in FIG. 26A. As thusdescribed, it is difficult in the prior art to further reduce the yokelength, which prevents improvements in high frequency characteristic.

OBJECTS AND SUMMARY OF THE INVENTION

It is a first object of the invention to provide a thin-film magnetichead and a method of manufacturing the same for precisely controlling atrack width of a recording head even when the track width is reduced,and for preventing a magnetic flux from saturating halfway through amagnetic path, and for achieving a reduction in a yoke length.

It is a second object of the invention to provide a thin-film magnetichead and a method of manufacturing the same for precisely controlling atrack width of a recording head even when the track width is reduced,and for preventing a magnetic flux from saturating halfway through amagnetic path, and for preventing writing of data in a region where datais not supposed to be written and preventing erasing of data in theregion where data is not supposed to be written.

A first thin-film magnetic head of the invention comprises: a mediumfacing surface that faces toward a recording medium; a reproducing headincluding: a magnetoresistive element; and a first shield layer and asecond shield layer for shielding the magnetoresistive element, portionsof the shield layers located on a side of the medium facing surfacebeing opposed to each other with the magnetoresistive element inbetween; and a recording head including: a first magnetic layer and asecond magnetic layer magnetically coupled to each other and includingmagnetic pole portions opposed to each other and placed in regions ofthe magnetic layers on a side of the medium facing surface, each of themagnetic layers including at least one layer; a gap layer providedbetween the pole portions of the first and second magnetic layers; and athin-film coil at least a part of which is placed between the first andsecond magnetic layers, the at least part of the coil being insulatedfrom the first and second magnetic layers. The first magnetic layerincludes: a first portion located in a region facing toward the at leastpart of the thin-film coil; and a second portion connected to a surfaceof the first portion facing toward the thin-film coil, the secondportion including a portion that forms one of the pole portions anddefines a throat height. The portion of the second portion of the firstmagnetic layer that defines the throat height has a length between anend thereof located in the medium facing surface and the other end, thelength being greater than a length of the magnetoresistive elementbetween an end thereof located in the medium facing surface and theother end. The at least part of the thin-film coil is located on a sideof the second portion of the first magnetic layer. The second magneticlayer defines a track width.

First and second methods of the invention are provided for manufacturinga thin-film magnetic head comprising: a medium facing surface that facestoward a recording medium; a reproducing head including: amagnetoresistive element; and a first shield layer and a second shieldlayer for shielding the magnetoresistive element, portions of the shieldlayers located on a side of the medium facing surface being opposed toeach other with the magnetoresistive element in between; and a recordinghead including: a first magnetic layer and a second magnetic layermagnetically coupled to each other and including magnetic pole portionsopposed to each other and placed in regions of the magnetic layers on aside of the medium facing surface, each of the magnetic layers includingat least one layer; a gap layer provided between the pole portions ofthe first and second magnetic layers; and a thin-film coil at least apart of which is placed between the first and second magnetic layers,the at least part of the coil being insulated from the first and secondmagnetic layers. In this head the second magnetic layer defines a trackwidth.

The first method of the invention includes the steps of: forming thereproducing head; forming the first magnetic layer; forming the gaplayer on the first magnetic layer; forming the second magnetic layer onthe gap layer; and forming the thin-film coil such that the at leastpart of the coil is placed between the first and second magnetic layers,the at least part of the coil being insulated from the first and secondmagnetic layers. The step of forming the first magnetic layer includesformation of: a first portion located in a region facing toward the atleast part of the thin-film coil; and a second portion connected to asurface of the first portion facing toward the thin-film coil, thesecond portion including a portion that forms one of the pole portionsand defines a throat height. The portion of the second portion of thefirst magnetic layer that defines the throat height is made to have alength between an end thereof located in the medium facing surface andthe other end, the length being greater than a length of themagnetoresistive element between an end thereof located in the mediumfacing surface and the other end. The at least part of the thin-filmcoil is located on a side of the second portion of the first magneticlayer in the step of forming the coil.

According to the first thin-film magnetic head or the first method ofthe invention, the throat height is defined by the second portion of thefirst magnetic layer. The track width is defined by the second magneticlayer. According to the invention, at least a part of the thin-film coilis located on a side of the second portion of the first magnetic layer.As a result, the second magnetic layer is formed on the flat surfacewith accuracy. It is thereby possible to precisely control the trackwidth as well as to prevent saturation of a magnetic flux in the secondmagnetic layer. According to the invention, it is possible that an endof at least a part of the thin-film coil is located near an end of thesecond portion of the first magnetic layer. It is thereby possible toreduce the yoke length. According to the invention, the portion of thesecond portion of the first magnetic layer that defines the throatheight has the length between an end thereof located in the mediumfacing surface and the other end, the length being greater than thelength of the magnetoresistive element between an end thereof located inthe medium facing surface and the other end. As a result, it is possibleto prevent saturation of a magnetic flux in the first magnetic layer.

According to the first thin-film magnetic head or the first method ofthe invention, a width of the second magnetic layer measured in aposition corresponding to the other end of the portion of the secondportion of the first magnetic layer may be greater than a width of thesecond magnetic layer measured in the medium facing surface.

According to the first thin-film magnetic head or the first method ofthe invention, the second magnetic layer may include: a portion having awidth equal to the track width and located closer to the medium facingsurface than the other portion of the second magnetic layer; and theother portion having a width greater than the track width, the width ofthe other portion decreasing toward the medium facing surface.

According to the first thin-film magnetic head or the first method, theportion of the second portion of the first magnetic layer that definesthe throat height has the length between the end thereof located in themedium facing surface and the other end, the length being preferably 150to 600 percent of the length of the magnetoresistive element between theend thereof located in the medium facing surface and the other end. Morepreferably, this length is 300 to 500 percent.

According to the first thin-film magnetic head or the first method, aninsulating layer may be further provided. The insulating layer coversthe at least part of the thin-film coil located on the side of thesecond portion of the first magnetic layer. A surface of the insulatinglayer facing toward the second magnetic layer is flattened together witha surface of the second portion facing toward the second magnetic layer.

According to the first thin-film magnetic head or the first method, thesecond magnetic layer may be made up of one layer.

According to the first thin-film magnetic head or the first method, thesecond magnetic layer may include: a pole portion layer including one ofthe pole portions that defines the track width; and a yoke portion layerforming a yoke portion and connected to the pole portion layer.

According to the first thin-film magnetic head or the first method, anend face of the yoke portion layer facing toward the medium facingsurface may be located at a distance from the medium facing surface. Inthis case, the pole portion layer may have a length between an endthereof located in the medium facing surface and the other end, thelength being greater than the length of the magnetoresistive elementbetween the end thereof located in the medium facing surface and theother end. In addition, the distance between the medium facing surfaceand the end face of the yoke portion layer facing toward the mediumfacing surface may be equal to or greater than the length of themagnetoresistive element. The thin-film coil may include: a first layerlocated on a side of the second portion of the first magnetic layer; anda second layer located on a side of the pole portion layer of the secondmagnetic layer. In this case, a first insulating layer and a secondinsulating layer may be further provided. The first insulating layercovers the first layer of the coil and has a surface facing toward thesecond magnetic layer, the surface being flattened together with asurface of the second portion of the first magnetic layer facing towardthe second magnetic layer. The second insulating layer covers the secondlayer of the coil and has a surface facing toward the yoke portionlayer, the surface being flattened together with a surface of the poleportion layer of the second magnetic layer facing toward the yokeportion layer.

According to the first thin-film magnetic head or the first method, theother end of the portion of the second portion of the first magneticlayer may have a shape of a straight line parallel to the medium facingsurface.

According to the first thin-film magnetic head or the first method, thesecond portion of the first magnetic layer may surround the at leastpart of the thin-film coil.

According to the first thin-film magnetic head or the first method, thesecond portion of the first magnetic layer may include a portion locatedcloser to the medium facing surface than the other part of the secondportion, the portion having a width smaller than a width of the otherpart of the second portion.

According to the first thin-film magnetic head or the first method, thesecond portion of the first magnetic layer may include: a center portionfacing the second magnetic layer and defining the throat height; andside portions formed at both ends of a width of the center portion. Atleast a part of the side portions has a length between an end thereoflocated in the medium facing surface and the other end, the length beinggreater than the throat height.

A second thin-film magnetic head of the invention comprises: a mediumfacing surface that faces toward a recording medium; a reproducing headincluding: a magnetoresistive element; and a first shield layer and asecond shield layer for shielding the magnetoresistive element, portionsof the shield layers located on a side of the medium facing surfacebeing opposed to each other with the magnetoresistive element inbetween; and a recording head including: a first magnetic layer and asecond magnetic layer magnetically coupled to each other and includingmagnetic pole portions opposed to each other and placed in regions ofthe magnetic layers on a side of the medium facing surface, each of themagnetic layers including at least one layer; a gap layer providedbetween the pole portions of the first and second magnetic layers; and athin-film coil at least a part of which is placed between the first andsecond magnetic layers, the at least part of the coil being insulatedfrom the first and second magnetic layers. The second magnetic layerincludes: a pole portion layer including one of the pole portions thatdefines the track width; and a yoke portion layer forming a yoke portionand connected to the pole portion layer. The pole portion layer has alength between an end thereof located in the medium facing surface andthe other end, the length being greater than a length of themagnetoresistive element between an end thereof located in the mediumfacing surface and the other end. An end face of the yoke portion layerfacing toward the medium facing surface is located at a distance fromthe medium facing surface, the distance between the medium facingsurface and the end face of the yoke portion layer being equal to orgreater than the length of the magnetoresistive element.

The second method of the invention includes the steps of: forming thereproducing head; forming the first magnetic layer; forming the gaplayer on the first magnetic layer; forming the second magnetic layer onthe gap layer; and forming the thin-film coil such that the at leastpart of the coil is placed between the first and second magnetic layers,the at least part of the coil being insulated from the first and secondmagnetic layers. In the step of forming the second magnetic layer, apole portion layer and a yoke portion layer are formed, the pole portionlayer including one of the pole portions that defines the track width,the yoke portion layer forming a yoke portion and being connected to thepole portion layer. The pole portion layer is made to have a lengthbetween an end thereof located in the medium facing surface and theother end, the length being greater than a length of themagnetoresistive element between an end thereof located in the mediumfacing surface and the other end. An end face of the yoke portion layerfacing toward the medium facing surface is located at a distance fromthe medium facing surface, the distance between the medium facingsurface and the end face of the yoke portion layer being equal to orgreater than the length of the magnetoresistive element.

According to the second thin-film magnetic head or the second method ofthe invention, the second magnetic layer is divided into the poleportion layer and the yoke portion layer. It is thereby possible toprecisely control the track width. According to the invention, the poleportion layer has the length between an end thereof located in themedium facing surface and the other end, the length being greater thanthe length of the magnetoresistive element between an end thereoflocated in the medium facing surface and the other end. An end face ofthe yoke portion layer facing toward the medium facing surface islocated at a distance from the medium facing surface, the distancebetween the medium facing surface and the end face of the yoke portionlayer being equal to or greater than the length of the magnetoresistiveelement. As a result, it is possible to prevent a magnetic flux fromsaturating halfway through the magnetic path and to prevent writing ofdata in a region where data is not supposed to be written and erasing ofdata where data is not supposed to be written.

According to the second thin-film magnetic head or the second method ofthe invention, the first magnetic layer may include: a first portionlocated in a region facing toward the at least part of the thin-filmcoil, and a second portion connected to a surface of the first portionfacing toward the thin-film coil, the second portion including a portionthat forms one of the pole portions and defines a throat height. Inaddition, the at least part of the thin-film coil may be located on aside of the second portion of the first magnetic layer.

According to the second thin-film magnetic head or the second method,the thin-film coil may include: a first layer located on a side of thesecond portion of the first magnetic layer; and a second layer locatedon a side of the pole portion layer of the second magnetic layer. Inthis case, a first insulating layer and a second insulating layer may befurther provided. The first insulating layer covers the first layer ofthe coil and has a surface facing toward the second magnetic layer, thesurface being flattened together with a surface of the second portion ofthe first magnetic layer facing toward the second magnetic layer. Thesecond insulating layer covers the second layer of the coil and has asurface facing toward the yoke portion layer, the surface beingflattened together with a surface of the pole portion layer of thesecond magnetic layer facing toward the yoke portion layer.

Other and further objects, features and advantages of the invention willappear more fully from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A and FIG. 1B are cross sections for illustrating a step in amethod of manufacturing a thin-film magnetic head of a first embodimentof the invention.

FIG. 2A and FIG. 2B are cross sections for illustrating a step thatfollows FIG. 1A and FIG. 1B.

FIG. 3A and FIG. 3B are cross sections for illustrating a step thatfollows FIG. 2A and FIG. 2B.

FIG. 4A and FIG. 4B are cross sections for illustrating a step thatfollows FIG. 3A and FIG. 3B.

FIG. 5A and FIG. 5B are cross sections for illustrating a step thatfollows FIG. 4A and FIG. 4B.

FIG. 6A and FIG. 6B are cross sections of the thin-film magnetic head ofthe first embodiment.

FIG. 7 is an explanatory view for illustrating the relationship betweena top view of the main part of the thin-film magnetic head of the firstembodiment and a cross-sectional view thereof.

FIG. 8 is a perspective view of the main part of the thin-film magnetichead of the first embodiment, a part of which is cut away.

FIG. 9 is a perspective view of the main part of the thin-film magnetichead of the first embodiment, a part of which is cut away.

FIG. 10 is a top view of a thin-film magnetic head of a secondembodiment of the invention.

FIG. 11 is a top view of a thin-film magnetic head of a third embodimentof the invention.

FIG. 12 is a top view of a thin-film magnetic head of a fourthembodiment of the invention.

FIG. 13 is a top view of a thin-film magnetic head of a fifth embodimentof the invention.

FIG. 14A and FIG. 14B are cross sections for illustrating a step in amethod of manufacturing a thin-film magnetic head of a sixth embodimentof the invention.

FIG. 15A and FIG. 15B are cross sections for illustrating a step thatfollows FIG. 14A and FIG. 14B.

FIG. 16A and FIG. 16B are cross sections for illustrating a step thatfollows FIG. 15A and FIG. 15B.

FIG. 17A and FIG. 17B are cross sections for illustrating a step thatfollows FIG. 16A and FIG. 16B.

FIG. 18A and FIG. 18B are cross sections for illustrating a step thatfollows FIG. 17A and FIG. 17B.

FIG. 19A and FIG. 19B are cross sections of the thin-film magnetic headof the sixth embodiment.

FIG. 20 is a top view of the thin-film magnetic head of the sixthembodiment.

FIG. 21 is a plot for illustrating the relationship between the sideerase property and the position of an end of a yoke portion layer facingtoward an air bearing surface shown in FIG. 19A and FIG. 19B.

FIG. 22 is a top view of a thin-film magnetic head of a seventhembodiment of the invention.

FIG. 23A and FIG. 23B are cross sections for illustrating a step in amethod of manufacturing a thin-film magnetic head of related art.

FIG. 24A and FIG. 24B are cross sections for illustrating a step thatfollows FIG. 23A and FIG. 23B.

FIG. 25A and FIG. 25B are cross sections for illustrating a step thatfollows FIG. 24A and FIG. 24B.

FIG. 26A and FIG. 26B are cross sections for illustrating a step thatfollows FIG. 25A and FIG. 25B.

FIG. 27 is a top view of the related-art thin-film magnetic head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of the invention will now be described in detailwith reference to the accompanying drawings.

[First Embodiment]

Reference is now made to FIG. 1A to FIG. 6A, FIG. 1B to FIG. 6B, andFIG. 7 to FIG. 9 to describe a thin-film magnetic head and a method ofmanufacturing the same of a first embodiment of the invention. FIG. 1Ato FIG. 6A are cross sections each orthogonal to an air bearing surface.FIG. 1B to FIG. 6B are cross sections of the pole portion each parallelto the air bearing surface.

In the manufacturing method, as shown in FIG. 1A and FIG. 1B, aninsulating layer 2 made of alumina (Al₂O₃), for example, whose thicknessis about 5 μm, is deposited on a substrate 1 made of aluminum oxide andtitanium carbide (Al₂O₃—TiC), for example. On the insulating layer 2 abottom shield layer 3 made of a magnetic material such as Permalloy andhaving a thickness of about 3 μm is formed for making a reproducinghead. The bottom shield layer 3 is formed through plating selectively onthe insulating layer 2 with a photoresist film as a mask, for example.Next, although not shown, an insulating layer of alumina, for example,having a thickness of 4 to 5 μm, for example, is formed over the entiresurface. This insulating layer is polished through chemical mechanicalpolishing (CMP), for example, so that the bottom shield layer 3 isexposed, and the surface is flattened.

Next, as shown in FIG. 2A and FIG. 2B, on the bottom shield layer 3, abottom shield gap film 4 having a thickness of about 20 to 40 nm, forexample, is formed as an insulating film. On the bottom shield gap film4, an MR element 5 for reproduction having a thickness of tens ofnanometers is formed. The MR element 5 may be fabricated throughselectively etching an MR film formed through sputtering. The MR element5 may be an element made of a magnetosensitive film exhibiting amagnetoresistivity, such as an AMR element, a GMR element, or a tunnelmagnetoresistive (TMR) element. Next, on the bottom shield gap film 4, apair of electrode layers 6 having a thickness of tens of nanometers areformed. The electrode layers 6 are electrically connected to the MRelement 5. Next, a top shield gap film 7 having a thickness of about 20to 40 nm, for example, is formed as an insulating film on the bottomshield gap film 4 and the MR element 5. The MR element 5 is embedded inthe shield gap films 4 and 7. An insulation material used for the shieldgap films 4 and 7 may be any of alumina, aluminum nitride, diamond-likecarbon (DLC), and so on. The shield gap films 4 and 7 may be fabricatedthrough sputtering or chemical vapor deposition (CVD) using trimethylaluminum (Al(CH₃)₃) and H₂O, for example. Through the use of CVD, it ispossible to make the thin and precise shield gap films 4 and 7 with fewpinholes.

Next, on the top shield gap film 7, a first portion 8 a of a top-shieldlayer-cum-bottom-pole-layer (called a bottom pole layer in the followingdescription) 8 having a thickness of about 1.0 to 1.5 μm is selectivelyformed. The bottom pole layer 8 is made of a magnetic material and usedfor both a reproducing head and a recording head. The bottom pole layer8 is made up of a second portion 8 b and the third portion 8 c describedlater, in addition to the first portion 8 a. The first portion 8 a isplaced in a region facing toward at least a part of a thin-film coildescribed later.

Next, the second portion 8 b and the third portion 8 c of the bottompole layer 8, each having a thickness of about 1.5 to 2.5 μm, are formedon the first portion 8 a. The second portion 8 b makes up a pole portionof the bottom pole layer 8 and is connected to a surface of the firstportion 8 a that faces toward the thin-film coil (on the upper side ofthe drawings). The third portion 8 c is provided for connecting thefirst portion 8 a to a top pole layer described later. The throat heightis defined by the position of an end of a portion of the second portion8 b opposite to the air bearing surface 30. This portion of the secondportion 8 b faces toward the top pole layer. That is, this portion ofthe second portion 8 b is the portion that defines the throat height.The zero throat height position is the position of the end of thisportion of the second portion 8 b.

The second portion 8 b and the third portion 8 c of the bottom polelayer 8 may be made of NiFe (80 weight % Ni and 20 weight % Fe), or NiFe(45 weight % Ni and 55 weight % Fe) as a high saturation flux densitymaterial and formed through plating, or may be made of a material suchas FeN or FeZrN as a high saturation flux density material throughsputtering. Alternatively, a material such as CoFe or a Co-baseamorphous material as a high saturation flux density material may beused.

Next, as shown in FIG. 3A and FIG. 3B, an insulating film 9 of alumina,for example, is formed over the entire surface. The thickness of theinsulating film 9 is about 0.3 to 0.6 μm.

Next, a photoresist is patterned through a photolithography process toform a frame 19 for making the thin-film coil through frame plating.Next, the thin-film coil 10 made of copper (Cu), for example, is formedby frame plating through the use of the frame 19. For example, thethickness of the coil 10 is about 1.0 to 2.0 μm and the pitch is 1.2 to2.0 μm. The frame 19 is then removed. In the drawings numeral 10 aindicates a portion for connecting the thin-film coil 10 to a conductivelayer (lead) described later.

Next, as shown in FIG. 4A and FIG. 4B, an insulating layer 11 ofalumina, for example, having a thickness of about 3 to 4 μm is formedover the entire surface. The insulating layer 11 is then polishedthrough CMP, for example, until the second portion 8 b and the thirdportion 8 c of the bottom pole layer 8 are exposed, and the surface isflattened. Although the thin-film coil 10 is not exposed in FIG. 4A andFIG. 4B, the coil 10 may be exposed.

Next, a recording gap layer 12 made of an insulating material whosethickness is 0.2 to 0.3 μm, for example, is formed on the second portion8 b and the third portion 8 c of the bottom pole layer 8 exposed and theinsulating layer 11. In general, the insulating material used for therecording gap layer 12 may be alumina, aluminum nitride, asilicon-dioxide-base material, a silicon-nitride-base material, ordiamond-like carbon (DLC) and so on.

Next, a portion of the recording gap layer 12 located on top of thethird portion 8 c is etched to form a contact hole for making themagnetic path. Portions of the recording gap layer 12 and the insulatinglayer 11 located on top of the connecting portion 10 a of the coil 10are etched to form a contact hole.

Next, as shown in FIG. 5A and FIG. 5B, on the recording gap layer 12,the top pole layer 13 having a thickness of about 2.0 to 3.0 μm isformed in a region extending from the air bearing surface 30 to theportion on top of the third portion 8 c of the bottom pole layer 8. Inaddition, the conductive layer 21 having a thickness of about 2.0 to 3.0μm is formed. The conductive layer 21 is connected to the portion 10 aof the thin-film coil 10. The top pole layer 13 is connected to thethird portion 8 c of the bottom pole layer 8 through the contact holeformed in the portion on top of the third portion 8 c.

The top pole layer 13 may be made of NiFe (80 weight % Ni and 20 weight% Fe), or NiFe (45 weight % Ni and 55 weight % Fe) as a high saturationflux density material and formed through plating, or may be made of amaterial such as FeN or FeZrN as a high saturation flux density materialthrough sputtering. Alternatively, a material such as CoFe or a Co-baseamorphous material as a high saturation flux density material may beused. In order to improve the high frequency characteristic, the toppole layer 13 may be made up of layers of inorganic insulating films andmagnetic layers of Permalloy, for example.

Next, the recording gap layer 12 is selectively etched through dryetching, using the top pole layer 13 as a mask. The dry etching may bereactive ion etching (RIE) using a chlorine-base gas such as BCl₂ orCl₂, or a fluorine-base gas such as CF₄ or SF₆, for example. Next, thesecond portion 8 b of the bottom pole layer 8 is selectively etched byabout 0.3 to 0.6 μm through argon ion milling, for example. A trimstructure as shown in FIG. 5B is thus formed. The trim structuresuppresses an increase in the effective track width due to expansion ofa magnetic flux generated during writing in a narrow track.

Next, an overcoat layer 17 of alumina, for example, having a thicknessof 20 to 40 μm is formed over the entire surface. The surface of theovercoat layer 17 is then flattened and pads (not shown) for electrodesare formed on the overcoat layer 17. Finally, lapping of the slider isperformed to form the air bearing surface 30 of the thin-film magnetichead including the recording head and the reproducing head. Thethin-film magnetic head of the embodiment is thus completed.

In this embodiment the bottom pole layer 8 made up of the first portion8 a, the second portion 8 b and the third portion 8 c corresponds to afirst magnetic layer of the invention. The top pole layer 13 correspondsto a second magnetic layer of the invention. The portion of the secondportion 8 b that faces toward the top pole layer 13 corresponds to aportion of a second portion of the first magnetic layer that defines thethroat height of the invention. Since the bottom pole layer 8 alsofunctions as the top shield layer, the bottom pole layer 8 correspondsto a second shield layer of the invention, too.

FIG. 7 is an explanatory view for illustrating the relationship betweena top view (an upper view of FIG. 7) of the main part of the thin-filmmagnetic head of the embodiment and a cross-sectional view (a lower viewof FIG. 7) thereof. The overcoat layer 17 and the other insulatinglayers and films are omitted in FIG. 7. In FIG. 7 ‘TH’ indicates thethroat height, ‘TH0’ indicates the zero throat height position, and‘MR-H’ indicates the MR height.

FIG. 8 is a perspective view of portions of the thin-film magnetic headof the embodiment including the layers from the bottom shield layer 3 tothe second portion 8 b of the bottom pole layer 8, the insulating film 9and the coil 10, a part of which is cut away. In FIG. 8 numeral 8Bindicates a portion of the second portion 8 b etched to make the trimstructure.

FIG. 9 is a perspective view of the portions of the head shown in FIG. 8to which the recording gap layer 12 and the top pole layer 13 are added,a part of which is cut away.

As described so far, the thin-film magnetic head of the embodimentcomprises the medium facing surface (air bearing surface 30) facingtoward a recording medium, the reproducing head and the recording head(induction-type magnetic transducer). The reproducing head has: the MRelement 5; and the bottom shield layer 3 and the top shield layer(bottom pole layer 8) for shielding the MR element 5. Portions of thebottom shield layer 3 and the top shield layer facing toward a recordingmedium are opposed to each other, the MR element 5 being placed betweenthe portions.

The recording head has the bottom pole layer 8 (including the firstportion 8 a, the second portion 8 b and the third portion 8 c) and thetop pole layer 13 magnetically coupled to each other, each of whichincludes at least one layer. The bottom pole layer 8 and the top polelayer 13 include pole portions opposed to each other and placed inregions on a side of the medium facing surface. The recording headfurther has: the recording gap layer 12 placed between the pole portionof the bottom pole layer 8 and the pole portion of the top pole layer13; and the thin-film coil 10 at least a part of which is placed betweenthe bottom pole layer 8 and the top pole layer 13, the at least part ofthe coil 10 being insulated from the bottom pole layer 8 and the toppole layer 13.

In this embodiment the bottom pole layer 8 includes: the first portion 8a located in a region facing toward at least a part of the thin-filmcoil 10; and the second portion 8 b connected to a surface of the firstportion 8 a that faces toward the coil 10 (the upper side of theaccompanying cross-sectional views). The second portion 8 b forms thepole portion and a portion of the second portion 8 b defines the throatheight. The coil 10 is located on a side of the second portion 8 b (onthe right side of the accompanying cross-sectional views).

In this embodiment throat height TH is the length of the portion of thesecond portion 8 b of the bottom pole layer 8 that defines the throatheight, the length between an end of the portion located in the airbearing surface 30 and the other end. (This length may be simply calledthe length of the second portion 8 b in the following description.)Throat height TH is greater than MR height, that is, the length of theMR element 5 between an end thereof located in the air bearing surface30 and the other end. The length of the second portion 8 b is preferably150 to 600 percent of MR height MR-H, and more preferably 300 to 500percent. In other words, if MR height MR-H is 0.5 μm, for example, thelength of the second portion 8 b is preferably 0.75 to 3.0 μm, and morepreferably 1.5 to 2.5 μm.

In the embodiment the portion of the second portion 8 b that facestoward the top pole layer 13 has an end opposite to the air bearingsurface 30, this end having the shape of a straight line parallel to theair bearing surface 30. The other part of the second portion 8 b has anend in the shape of an arc that approximates to the shape of theperimeter of the thin-film coil 10. Since the portion of the secondportion 8 b that faces toward the top pole layer 13 has the end havingthe above-described shape in this embodiment, it is possible toprecisely control the throat height and the zero throat height position.

In the embodiment the track width is defined by the top pole layer 13.As shown in FIG. 7, the top pole layer 13 has a first portion 13A, asecond portion 13B and a third portion 13C in the order in which theclosest to the air bearing surface 30 comes first. The first portion 13Ahas a width equal to the recording track width. The second portion 13Bis greater than the first portion 13A in width. The third portion 13C isgreater than the second portion 13B in width.

The width of the third portion 13C gradually decreases toward the airbearing surface 30. It is preferred that each of lateral edges of aportion of the third portion 13C having a varying width forms an angleof 30 to 60 degrees with respect to the direction orthogonal to the airbearing surface 30, each of the lateral edges being located at each endof the width of the third portion 13C. The width of the second portion13B gradually decreases toward the air bearing surface 30, too.

In the top pole layer 13 there are edges linking lateral edges of thefirst portion 13A orthogonal to the air bearing surface 30 to lateraledges of the second portion 13B located at ends of the width of thesecond portion 13B. These edges linking the lateral edges of the firstportion 13A to the lateral edges of the second portion 13B are parallelto the air bearing surface 30. Similarly, the top pole layer 13 hasedges linking the lateral edges of the second portion 13B to the lateraledges of the third portion 13C. These edges linking the lateral edges ofthe second portion 13B to the lateral edges of the third portion 13C areparallel to the air bearing surface 30.

In the top pole layer 13 the interface between the first portion 13A andthe second portion 13B is located near the zero MR height position (theposition of an end of the MR element 5 opposite to the air bearingsurface 30).

In the top pole layer 13 the interface between the second portion 13Band the third portion 13C (the position near the stepped portionsbetween the portion 13B and the portion 13C shown in FIG. 7) is locatedcloser to the air bearing surface 30 (that is, on the left side of FIG.7) than zero throat height position TH0, that is, the position of an endof the portion of the second portion 8 b that faces toward the top polelayer 13, the end being opposite to the air bearing surface 30 (on theright side of FIG. 7). As a result, in this embodiment, width W1 of thetop pole layer 13 at zero throat height position TH0 is greater thanrecording track width W2, that is, the width of the first portion 13A.

According to the embodiment thus described, the throat height is definedby the second portion 8 b of the bottom pole layer 8. The thin-film coil10 is located on the first portion 8 a of the bottom pole layer 8 and ona side of the second portion 8 b. The top surface of the insulatinglayer 11 covering the coil 10 is flattened, together with the topsurface of the second portion 8 b. As a result, the top pole layer 13that defines the recording track width is formed on the flat surface.Therefore, according to the embodiment, it is possible to form the toppole layer 13 with accuracy and to precisely control the recording trackwidth even if the recording track width is reduced down to thehalf-micron or quarter-micron order.

According to the embodiment, the width of the top pole layer 13 in thezero throat height position is greater than the recording track width.It is thereby possible to prevent a magnetic flux from saturating nearthe zero throat height position. In addition, the width of the top polelayer 13 gradually decreases toward the air bearing surface 30.Therefore, it is impossible that the cross-sectional area of themagnetic path abruptly decreases. Saturation of a magnetic flux halfwaythrough the magnetic path is thereby prevented. According to theembodiment, it is thereby possible to utilize the magnetomotive forcegenerated by the thin-film coil 10 for writing with efficiency and toimprove the overwrite property.

According to the embodiment, the top pole layer 13 that defines therecording track width is formed on the flat surface. As a result, it ispossible to prevent an increase in the width of the first portion 13Athat defines the recording track width when the width of the top polelayer 13 in the zero throat height position is made greater than therecording track width as described above. If the top pole layer isformed on the apex, the width of the portion of the top pole layer thatdefines the recording track width is likely to increase, too, when thewidth of the top pole layer in the zero throat height position is madegreater than the recording track width.

In the embodiment an end of the second portion 13B of the top pole layer13 on a side of the air bearing surface 30 is parallel to the airbearing surface 30. The first portion 13A of the top pole layer 13 isconnected to this end of the second portion 13B. Therefore, a photomaskused for making the top pole layer 13 through photolithography has ashape including a side corresponding to the end of the second portion13B on the side of the air bearing surface 30 and an additional concaveor convex portion corresponding to the first portion 13A. Whether theportion corresponding to the first portion 13A is concave or convexdepends on whether a negative photomask or a positive photomask is used.The top pole layer 13 is formed on the flat surface through the use ofthe photomask in the above-described shape. It is thereby possible toprecisely control the width of the first portion 13A, that is, therecording track width.

According to the embodiment, the throat height is defined by the secondportion 8 b of the bottom pole layer 8. The length of the second portion8 b is greater than MR height MR-H, that is, the length of the MRelement 5 between the end thereof located in the air bearing surface 30and the other end. As a result, the areas of the first portion 8 a andthe second portion 8 b touching each other are made greater. It isthereby possible to prevent a magnetic flux from saturating in thoseareas.

The greater the length of the second portion 8 b than MR height MR-H,the greater are the areas of the first portion 8 a and the secondportion 8 b touching each other. Therefore, if the difference betweenthe length of the second portion 8 b and MR height MR-H is small, theeffect of preventing saturation of the flux is reduced, and the degreeof an improvement in overwrite property is reduced. On the other hand,if the length of the second portion 8 b is too great, the yoke length ismade greater and the overwrite property is reduced, conversely.Therefore, there is a range of the preferred length of the secondportion 8 b. To be specific, the length of the second portion 8 b ispreferably 150 to 600 percent of MR height MR-H, and more preferably 300to 500 percent, as mentioned above.

According to the embodiment as thus described, it is possible toprecisely control the recording track width and to prevent a magneticflux from saturating halfway through the magnetic path even if therecording track width is reduced.

In the embodiment the thin-film coil 10 is located on a side of thesecond portion 8 b of the bottom pole layer 8 and formed on the flatinsulating film 9. It is thereby possible to form the thin-film coil 10of small dimensions with accuracy. Furthermore, according to theembodiment, it is possible that an end of the coil 10 is placed near thezero throat height position, that is, near the end of the second portionlayer 8 b opposite to the air bearing surface 30, since no apex exists.

As thus described, according to the embodiment, the yoke length isreduced by about 30 to 40 percent of that of a prior-art head, forexample. As a result, it is possible to utilize a magnetomotive forcegenerated by the thin-film coil 10 for writing with efficiency. It istherefore possible to provide a thin-film magnetic head having arecording head with an excellent high frequency characteristic, anexcellent nonlinear transition shift (NLTS) characteristic and anexcellent overwrite property.

According to the embodiment, a reduction in yoke length is achieved. Asa result, it is possible to greatly reduce the entire length of thethin-film coil 10 without changing the number of turns of the coil. Theresistance of the coil 10 is thereby reduced. It is therefore possibleto reduce the thickness of the coil 10.

According to the embodiment, the insulating film 9 is provided betweenthe first portion 8 a of the bottom pole layer 8 and the thin-film coil10. The insulating film 9 is thin and made of an inorganic material thatachieves sufficient insulation strength. High insulation strength isthereby obtained between the first portion 8 a and the coil 10.

In the embodiment the thin-film coil 10 is covered with the insulatinglayer 11 made of an inorganic insulation material. It is therebypossible to prevent the pole portion from protruding toward a recordingmedium due to expansion resulting from heat generated around the coil 10when the thin-film magnetic head is used.

[Second Embodiment]

Reference is now made to FIG. 10 to describe a thin-film magnetic headand a method of manufacturing the same of a second embodiment of theinvention. FIG. 10 is a top view of the main part of the thin-filmmagnetic head of the embodiment, wherein an overcoat layer and the otherinsulating layers and films are omitted.

In the second embodiment the first portion 8 a of the bottom pole layer8 is formed in a region greater than the region of the first embodiment.To be specific, the first portion 8 a is formed in the region greaterthe region where the entire thin-film coil 10 is placed. In addition,the second portion 8 b of the bottom pole layer 8 is formed to surroundthe coil 10 in the second embodiment. In this embodiment throat heightTH is the length of a portion of the second portion 8 b that defines thethroat height, the length between an end of this portion located in theair bearing surface 30 and the other end. As in the first embodiment,throat height TH is greater than MR height MR-H, that is, the length ofthe MR element 5 between an end thereof located in the air bearingsurface 30 and the other end.

According to the second embodiment, it is possible to flatten theinsulating layer 11 with further accuracy since the second portion 8 bhas the geometry described above.

The top pole layer 13 of the second embodiment has the first portion13A, the second portion 13B and the third portion 13C in the order inwhich the closest to the air bearing surface 30 comes first. The firstportion 13A and the second portion 13B have geometries similar to thoseof the first embodiment. The width of the third portion 13C varies inthe following manner. The width thereof gradually increases from an endof the third portion 13C closer to the air bearing surface 30, formingan angle of 30 to 60 degrees, for example, with respect to the directionorthogonal to the air bearing surface 30. The width then increases,forming a greater angle, and finally becomes constant.

The remainder of the configuration, functions and effects of theembodiment are similar to those of the first embodiment.

[Third Embodiment]

Reference is now made to FIG. 11 to describe a thin-film magnetic headand a method of manufacturing the same of a third embodiment of theinvention. FIG. 11 is a top view of the main part of the thin-filmmagnetic head of the embodiment, wherein an overcoat layer and the otherinsulating layers and films are omitted.

In the third embodiment the second portion 8 b of the bottom pole layer8 has a T-shape in which a portion closer to the air bearing surface 30is smaller than the other portion in width. An end of the second portion8 b opposite to the air bearing surface 30 has the shape of a straightline parallel to the air bearing surface 30, and is located at zerothroat height position TH0.

According to the embodiment, since the second portion 8 b has thegeometry as described above, it is possible to reduce the width of thesecond portion 8 b in the air bearing surface 30 and to prevent anincrease in effective track width. In addition, the width of the secondportion 8 b decreases toward the air bearing surface 30 in astep-by-step manner. It is thereby possible to prevent a magnetic fluxfrom saturating in the bottom pole layer 8. Furthermore, it is possibleto precisely control the throat height and the zero throat heightposition since the end of the second portion 8 b opposite to the airbearing surface 30 has the shape of a straight line parallel to the airbearing surface 30.

The remainder of the configuration, functions and effects of theembodiment are similar to those of the first embodiment.

[Fourth Embodiment]

Reference is now made to FIG. 12 to describe a thin-film magnetic headand a method of manufacturing the same of a fourth embodiment of theinvention. FIG. 12 is a top view of the main part of the thin-filmmagnetic head of the embodiment, wherein an overcoat layer and the otherinsulating layers and films are omitted.

In the fourth embodiment the second portion 8 b of the bottom pole layer8 has: a center portion 8 b ₁ that faces toward the top pole layer 13and defines the throat height; and side portions 8 b ₂ and 8 b ₃ placedat ends of the width of the center portion 8 b ₁. An end of the centerportion 8 b ₁ opposite to the air bearing surface 30 has the shape of astraight line parallel to the air bearing surface 30, and is located atzero throat height position TH0. The length of each of the side portions8 b ₂ and 8 b ₃ between an end located in the air bearing surface 30 andthe other end is equal to the throat height at the interface between thecenter portion 8 b ₁ and each of the side portions 8 b ₂ and 8 b ₃. Thelength increases as the distance from the interface becomes greater, andfinally becomes constant.

The top pole layer 13 of this embodiment has the first portion 13A and asecond portion 13D in the order in which the closest to the air bearingsurface 30 comes first. The width of the first portion 13A is equal tothe recording track width. The width of the second portion 13D is equalto the recording track width at the interface with the first portion13A, and gradually increases as the distance from the air bearingsurface 30 increases. It is preferred that each of the lateral edges ofthe portion of the second portion 13D having the increasing width formsan angle of 30 to 60 degrees with respect to the direction orthogonal tothe air bearing surface 30. The interface between the first portion 13Aand the second portion 13D is located closer to the air bearing surface30 than zero throat height position TH0. Therefore, width W1 of the toppole layer 13 at zero throat height position TH0 is greater thanrecording track width W2, that is, the width of the first portion 13A.It is preferred that the interface between the first portion 13A and thesecond portion 13D is located at a distance of 0 to 1.0 μm from the zeroMR height position toward the direction opposite to the air bearingsurface 30.

According to the embodiment, the end of the center portion 8 b ₁ of thesecond portion 8 b of the bottom pole layer 8 opposite to the airbearing surface 30 has the shape of a straight line parallel to the airbearing surface 30. As a result, it is possible to precisely control thethroat height and the zero throat height position. In addition, thelength of each of the side portions 8 b ₂ and 8 b ₃ of the secondportion 8 b between the end located in the air bearing surface 30 andthe other end is greater than the length of the center portion 8 b ₁,except the interface between the center portion 8 b ₁ and each of theside portions 8 b ₂ and 8 b ₃. As a result, the volume of the secondportion 8 b and the areas of the first portion 8 a and the secondportion 8 b touching each other are made greater, compared to the casein which the entire second portion 8 b has a constant length. It isthereby possible to prevent a magnetic flux from saturating in theportion connecting the first portion 8 a to the second portion 8 b evenwhen the throat height is small.

According to the embodiment, the width of the second portion 13Dgradually decreases toward the air bearing surface 30. It is therebypossible to prevent a magnetic flux from saturating in the top polelayer 13.

The remainder of the configuration, functions and effects of theembodiment are similar to those of the first embodiment.

[Fifth Embodiment]

Reference is now made to FIG. 13 to describe a thin-film magnetic headand a method of manufacturing the same of a fifth embodiment of theinvention. FIG. 13 is a top view of the main part of the thin-filmmagnetic head of the embodiment, wherein an overcoat layer and the otherinsulating layers and films are omitted.

In the fifth embodiment the second portion 8 b of the bottom pole layer8 has: the center portion 8 b ₁ that faces toward the top pole layer 13and defines the throat height; and the side portions 8 b ₂ and 8 b ₃placed at ends of the width of the center portion 8 b ₁. An end of thecenter portion 8 b ₁ opposite to the air bearing surface 30 has theshape of a straight line parallel to the air bearing surface 30, and islocated at zero throat height position TH0. The length of each of theside portions 8 b ₂ and 8 b ₃ between an end located in the air bearingsurface 30 and the other end is equal to the throat height at theinterface between the center portion 8 b ₁ and each of the side portions8 b ₂ and 8 b ₃. The length increases as the distance from the interfacebecomes greater, and finally becomes constant. The portion of each ofthe side portions 8 b ₂ and 8 b ₃ having the varying width between theend located in the air bearing surface 30 and the other end has the endopposite to the air bearing surface 30 located along each of the ends ofthe third portion 13C of the top pole layer 13 located at each end ofthe width of the third portion 13C.

According to the embodiment, the end of the center portion 8 b ₁ of thesecond portion 8 b of the bottom pole layer 8 opposite to the airbearing surface 30 has the shape of a straight line parallel to the airbearing surface 30. As a result, it is possible to precisely control thethroat height and the zero throat height position. In addition, thelength of each of the side portions 8 b ₂ and 8 b ₃ of the secondportion 8 b between the end located in the air bearing surface 30 andthe other end is greater than the length of the center portion 8 b ₁,except the interface between the center portion 8 b ₁ and each of theside portions 8 b ₂ and 8 b ₃. As a result, the volume of the secondportion 8 b and the areas of the first portion 8 a and the secondportion 8 b touching each other are made greater, compared to the casein which the entire second portion 8 b has a constant length. It isthereby possible to prevent a magnetic flux from saturating in theportion connecting the first portion 8 a to the second portion 8 b evenwhen the throat height is small.

The remainder of the configuration, functions and effects of theembodiment are similar to those of the first embodiment.

[Sixth Embodiment]

Reference is now made to FIG. 14A to FIG. 19A, FIG. 14B to FIG. 19B, andFIG. 20 to describe a thin-film magnetic head and a method ofmanufacturing the same of a sixth embodiment of the invention. FIG. 14Ato FIG. 19A are cross sections each orthogonal to an air bearingsurface. FIG. 14B to FIG. 19B are cross sections of the pole portioneach parallel to the air bearing surface.

In the manufacturing method, as shown in FIG. 14A and FIG. 14B, theinsulating layer 2 made of alumina (Al₂O₃), for example, whose thicknessis about 5 μm, is deposited on the substrate 1 made of aluminum oxideand titanium carbide (Al₂O₃—TiC), for example. On the insulating layer 2the bottom shield layer 3 made of a magnetic material such as Permalloyand having a thickness of about 3 μm is selectively formed for making areproducing head. Next, although not shown, an insulating layer ofalumina, for example, having a thickness of 4 to 5 μm, for example, isformed over the entire surface. This insulating layer is polishedthrough CMP, for example, so that the bottom shield layer 3 is exposed,and the surface is flattened.

Next, as shown in FIG. 15A and FIG. 15B, on the bottom shield layer 3,the bottom shield gap film 4 having a thickness of about 20 to 40 nm,for example, is formed as an insulating film. On the bottom shield gapfilm 4, the MR element 5 for reproduction having a thickness of tens ofnanometers is formed. Next, on the bottom shield gap film 4, a pair ofelectrode layers 6 having a thickness of tens of nanometers are formed.The electrode layers 6 are electrically connected to the MR element 5.Next, the top shield gap film 7 having a thickness of about 20 to 40 nm,for example, is formed as an insulating film on the bottom shield gapfilm 4 and the MR element 5. The MR element 5 is embedded in the shieldgap films 4 and 7.

Next, on the top shield gap film 7, the first portion 8 a of the bottompole layer 8 having a thickness of about 1.0 to 2.0 μm is selectivelyformed. The first portion 8 a is made of a magnetic material and placedin a region facing toward at least a part of a thin-film coil describedlater.

Next, as shown in FIG. 16A and FIG. 16B, the second portion 8 b and thethird portion 8 c of the bottom pole layer 8, each having a thickness ofabout 1.5 to 2.5 μm, are formed on the first portion 8 a. The secondportion 8 b makes up a pole portion of the bottom pole layer 8 and isconnected to a surface of the first portion 8 a that faces toward thethin-film coil. The third portion 8 c is provided for connecting thefirst portion 8 a to a top pole layer described later. The throat heightis defined by the position of an end of a portion of the second portion8 b opposite to the air bearing surface 30. This portion of the secondportion 8 b faces toward the top pole layer. That is, the position ofthe end of this portion of the second portion 8 b is the zero throatheight position.

Next, the insulating film 9 of alumina, for example, is formed over theentire surface. The thickness of the insulating film 9 is about 0.3 to0.6 μm.

Next, a photoresist is patterned through a photolithography process toform the frame 19 for making the thin-film coil through frame plating.Next, a first layer 31 of the thin-film coil made of copper, forexample, is formed by frame plating through the use of the frame 19. Forexample, the thickness of the first layer 31 is about 1.0 to 2.0 μm andthe pitch is 1.2 to 2.0 μm. The frame 19 is then removed. In thedrawings numeral 31 a indicates a portion for connecting the first layer31 to a second layer of the coil described later.

Next, as shown in FIG. 17A and FIG. 17B, the insulating layer 32 ofalumina, for example, having a thickness of about 3 to 4 μm is formedover the entire surface. The insulating layer 32 is then polishedthrough CMP, for example, until the second portion 8 b and the thirdportion 8 c of the bottom pole layer 8 are exposed, and the surface isflattened. Although the first layer 31 of the coil is not exposed inFIG. 17A and FIG. 17B, the first layer 31 may be exposed.

Next, as shown in FIG. 18A and FIG. 18B, the recording gap layer 12 madeof an insulating material whose thickness is 0.2 to 0.3 μm, for example,is formed on the second portion 8 b and the third portion 8 c of thebottom pole layer 8 exposed and the insulating layer 32. Next, a portionof the recording gap layer 12 located on top of the third portion 8 c isetched to form a contact hole for making the magnetic path.

Next, on the recording gap layer 12, a pole portion layer 41 having athickness of 2 to 3 μm, for example, is formed. The pole portion layer41 includes a pole portion of the top pole layer that defines therecording track width. In addition, a magnetic layer 42 having athickness of 2 to 3 μm is formed in the contact hole provided in theportion on top of the third portion 8 c of the bottom pole layer 8. Themagnetic layer 42 is provided for connecting the bottom pole layer 8 toa yoke portion layer of the top pole layer described later. In thisembodiment the length of the pole portion layer 41 of the top pole layerbetween an end located in the air bearing surface 30 and the other endis greater than the length of the MR element 5 between an end located inthe air bearing surface 30 and the other end. Furthermore, this lengthof the pole portion layer 41 is equal to or greater than the length ofthe portion of the second portion 8 b of the bottom pole layer 8 thatdefines the throat height, the length between an end located in the airbearing surface 30 and the other end.

The pole portion layer 41 and the magnetic layer 42 of the top polelayer may be made of NiFe (80 weight % Ni and 20 weight % Fe), or NiFe(45 weight % Ni and 55 weight % Fe) as a high saturation flux densitymaterial and formed through plating, or may be made of a material suchas FeN or FeZrN as a high saturation flux density material throughsputtering. Alternatively, a material such as CoFe or a Co-baseamorphous material as a high saturation flux density material may beused.

Next, the recording gap layer 12 is selectively etched through dryetching, using the pole portion layer 41 as a mask. The dry etching maybe reactive ion etching (RIE) using a chlorine-base gas such as BCl₂ orCl₂, or a fluorine-base gas such as CF₄ or SF₆, for example. Next, thesecond portion 8 b of the bottom pole layer 8 is selectively etched byabout 0.3 to 0.6 μm through argon ion milling, for example. A trimstructure as shown in FIG. 18B is thus formed.

Next, an insulating film 33 of alumina, for example, having a thicknessof about 0.3 to 0.6 μm is formed over the entire surface. Next, portionsof the insulating film 33, the recording gap layer 12 and the insulatinglayer 32 located on top of the connection portion 31 a are etched toform a contact hole. Next, a second layer 34 of the thin-film coil madeof copper, for example, is formed by frame plating. For example, thethickness of the second layer 34 is about 1.0 to 2.0 μm and the pitch is1.2 to 2.0 μm. In the drawings numeral 34 a indicates a portion forconnecting the second layer 34 to the first layer 31 of the coil throughthe above-mentioned contact hole.

Next, as shown in FIG. 19A and FIG. 19B, an insulating layer 35 ofalumina, for example, having a thickness of about 3 to 4 μm is formedover the entire surface. The insulating layer 35 is then polishedthrough CMP, for example, so that the pole portion layer 41 and themagnetic layer 42 of the top pole layer are exposed, and the surface isflattened. Although the second layer 34 is not exposed in FIG. 19A andFIG. 19B, the second layer 34 may be exposed. If the second layer 34 isexposed, another insulating layer is formed to cover the second layer 34and the insulating layer 35.

Next, a yoke portion layer 43 having a thickness of about 2 to 3 μm, forexample, is formed on the pole portion layer 41 and the magnetic layer42 of the top pole layer flattened and the insulating layer 35. The yokeportion layer 43 provided for the recording head is made of a magneticmaterial and forms a yoke portion of the top pole layer. The yokeportion layer 43 is in contact and magnetically coupled to the thirdportion 8 c of the bottom pole layer 8 through the magnetic layer 42.The yoke portion layer 43 may be made of NiFe (80 weight % Ni and 20weight % Fe), or NiFe (45 weight % Ni and 55 weight % Fe) as a highsaturation flux density material and formed through plating or may bemade of a material such as FeN or FeZrN as a high saturation fluxdensity material through sputtering. Alternatively, a material such asCoFe or a Co-base amorphous material as a high saturation flux densitymaterial may be used. To improve the high frequency characteristic, theyoke portion layer 43 may be made of a number of layers of inorganicinsulating films and magnetic layers of Permalloy, for example.

In this embodiment an end face of the yoke portion layer 43 facingtoward the air bearing surface 30 is located at a distance from the airbearing surface 30 (that is, on the right side of FIG. 19A). In thisembodiment, in particular, the distance between the air bearing surface30 and the end of the yoke portion layer 43 facing toward the airbearing surface 30 is equal to or greater than the length of the MRelement 5 between an end thereof located in the air bearing surface 30and the other end.

Next, an overcoat layer 37 of alumina, for example, having a thicknessof 20 to 40 μm is formed over the entire surface. The surface of theovercoat layer 37 is then flattened and pads (not shown) for electrodesare formed on the overcoat layer 37. Finally, lapping of the slider isperformed to form the air bearing surface 30 of the thin-film magnetichead including the recording head and the reproducing head. Thethin-film magnetic head of the embodiment is thus completed.

In this embodiment the top pole layer made up of the pole portion layer41, the magnetic layer 42 and the yoke portion layer 43 corresponds tothe second magnetic layer of the invention.

FIG. 20 is a top view of the main part of the thin-film magnetic head ofthe embodiment, wherein the overcoat layer and the other insulatinglayers and films are omitted. In FIG. 20 ‘TH’ indicates the throatheight, ‘TH0’ indicates the zero throat height position, and ‘MR-H’indicates the MR height.

In this embodiment the bottom pole layer 8 includes: the first portion 8a located in the region facing toward the first layer 31 of thethin-film coil; and the second portion 8 b connected to a surface of thefirst portion 8 a that faces toward the first layer 31 of the coil. Thesecond portion 8 b forms the pole portion and a portion of the secondportion 8 b defines the throat height. The first layer 31 of the coil islocated on a side of the second portion 8 b. In this embodiment throatheight TH is the length of the portion of the second portion 8 b thatdefines the throat height, the length between an end of the portionlocated in the air bearing surface 30 and the other end. (This lengthmay be simply called the length of the second portion 8 b in thefollowing description.) As in the first embodiment, throat height TH isgreater than MR height MR-H, that is, the length of the MR element 5between an end thereof located in the air bearing surface 30 and theother end. The length of the second portion 8 b is preferably 150 to 600percent of MR height MR-H, and more preferably 300 to 500 percent. Inother words, if MR height MR-H is 0.5 μm, for example, the length of thesecond portion 8 b is preferably 0.75 to 3.0 μm, and more preferably 1.5to 2.5 μm.

In the embodiment the track width is defined by the pole portion layer41 of the top pole layer. As shown in FIG. 20, the pole portion layer 41has a first portion 41A, a second portion 41B and a third portion 41C inthe order in which the closest to the air bearing surface 30 comesfirst. The first portion 41A has a width equal to the recording trackwidth. The second portion 41B is greater than the first portion 41A inwidth. The width of the third portion 41C is equal to the width of thesecond portion 41B at the interface between the third portion 41C andthe second portion 41B. The width of the third portion 41C increasesfrom this interface with an increase in the distance from the airbearing surface 30, and the width finally becomes constant.

The pole portion layer 41 has edges linking lateral edges of the firstportion 41A orthogonal to the air bearing surface 30 to lateral edges ofthe second portion 41B orthogonal to the air bearing surface 30. Theseedges linking the lateral edges of the first portion 41A to the lateraledges of the second portion 41B are parallel to the air bearing surface30.

In the pole portion layer 41 the interface between the first portion 41Aand the second portion 41B is located near the zero MR height position.

In the pole portion layer 41 the interface between the second portion41B and the third portion 41C is located closer to the air bearingsurface 30 than zero throat height position TH0, that is, the positionof an end of the portion of the second portion 8 b that faces toward thepole portion layer 41, the end opposite to the air bearing surface 30.As a result, in this embodiment, width W1 of the pole portion layer 41at zero throat height position TH0 is greater than recording track widthW2, that is, the width of the first portion 41A.

The yoke portion layer 43 of the top pole layer has a first portion 43Aand a second portion 43B in the order in which the closest to the airbearing surface 30 comes first. The first portion 43A has a width nearlyequal to the greatest width of the third portion 41C of the pole portionlayer 41. The width of the second portion 43B is equal to the width ofthe first portion 43A at the interface between the first portion 43A andthe second portion 43B. The width of the second portion 43B increasesfrom this interface with an increase in the distance from the airbearing surface 30, and the width finally becomes constant. The firstportion 43A is located so as to nearly overlay the second portion 41Band the third portion 41C of the pole portion layer 41.

According to the embodiment thus described, the throat height is definedby the second portion 8 b of the bottom pole layer 8. The first layer 31of the thin-film coil is located on the first portion 8 a of the bottompole layer 8 and on a side of the second portion 8 b. The top surface ofthe insulating layer 32 covering the first layer 31 is flattened,together with the top surface of the second portion 8 b. In addition,the top pole layer is divided into the pole portion layer 41 and theyoke portion layer 43. As a result, the pole portion layer 41 of the toppole layer that defines the recording track width is formed on the flatsurface. Therefore, according to the embodiment, it is possible to formthe pole portion layer 41 with accuracy and to precisely control therecording track width even if the recording track width is reduced downto the half-micron or quarter-micron order.

According to the embodiment, the width of the pole portion layer 41 atthe zero throat height position is greater than the recording trackwidth. It is thereby possible to prevent a magnetic flux from saturatingin the pole portion layer 41 in the neighborhood of the zero throatheight position. In addition, the width of the pole portion layer 41gradually decreases toward the air bearing surface 30. Therefore, it isimpossible that the cross-sectional area of the magnetic path abruptlydecreases. Saturation of a magnetic flux halfway through the magneticpath is thereby prevented. Furthermore, the width of the pole portionlayer 41 at the zero throat height position is greater than therecording track width. As a result, the areas of the pole portion layer41 and the yoke portion layer 43 touching each other are increased. Itis thereby possible to prevent a magnetic flux from saturating in theportions of the pole portion layer 41 and the yoke portion layer 43touching each other. According to the embodiment, it is thereby possibleto utilize the magnetomotive force generated by the layers 31 and 34 ofthe coil for writing with efficiency and to improve the overwriteproperty.

According to the embodiment, the pole portion layer 41 that defines therecording track width is formed on the flat surface. As a result, it ispossible to prevent an increase in the width of the first portion 41Athat defines the recording track width when the width of the poleportion layer 41 at the zero throat height position is made greater thanthe recording track width as described above.

In the embodiment an end of the second portion 41B of the pole portionlayer 41 on a side of the air bearing surface 30 is parallel to the airbearing surface 30. The first portion 41A of the pole portion layer 41is connected to this end of the second portion 41B. Therefore, aphotomask used for making the pole portion layer 41 throughphotolithography has a shape including a side corresponding to the endof the second portion 41B on the side of the air bearing surface 30 andan additional concave or convex portion corresponding to the firstportion 41A. The pole portion layer 41 is formed on the flat surfacethrough the use of the photomask in the above-described shape. It isthereby possible to precisely control the width of the first portion41A, that is, the recording track width.

In the embodiment the second layer 34 of the thin-film coil is locatedon a side of the pole portion layer 41 of the top pole layer. The topsurface of the insulating layer 35 covering the second layer 34 isflattened, together with the top surface of the pole portion layer 41.As a result, the yoke portion layer 43 of the top pole layer is formedon the flat surface, too. It is thereby possible to form the yokeportion layer 43 of small dimensions. So-called ‘side write’ and ‘sideerase’ are thus prevented.

In the embodiment an end face of the yoke portion layer 43 facing towardthe air bearing surface 30 is located at a distance from the air bearingsurface 30. As a result, it is impossible that the yoke portion layer 43is exposed from the air bearing surface 30 even if the throat height islow. Side write and side erase are thereby prevented.

According to the embodiment, the length of the pole portion layer 41between an end thereof facing toward the air bearing surface 30 and theother end is greater than the MR height, that is, the length of the MRelement 5 between the end thereof located in the air bearing surface 30and the other end. In addition, the end face of the yoke portion layer43 facing toward the air bearing surface 30 is located at a distancefrom the air bearing surface 30. Therefore, portions of the pole portionlayer 41 and the yoke portion layer 43 touch each other in the regionfarther from the air bearing surface 30 than the zero throat heightposition, too. As a result, according to the embodiment, side write andside erase are prevented since the end face of the yoke portion layer 43facing toward the air bearing surface 30 is located at a distance fromthe air bearing surface 30. At the same time, it is possible to preventan abrupt decrease in the cross-sectional area of the magnetic path inthe top pole layer and to prevent a magnetic flux from saturatinghalfway through the magnetic path.

In the embodiment the distance between the air bearing surface 30 andthe end of the yoke portion layer 43 facing toward the air bearingsurface 30 is equal to or greater than the MR height, that is, thelength of the MR element 5 between an end thereof located in the airbearing surface 30 and the other end.

Reference is now made to FIG. 21 to describe a result of an experimentperformed for determining the relationship between the side eraseproperty and the position of the end of the yoke portion layer 43 facingtoward the air bearing surface 30. Thin-film magnetic heads used forthis experiment were of seven types in one of which the position of theend of the yoke portion layer 43 was located in the air bearing surface30 (shown as ABS in FIG. 21). In the other six types the distancebetween the air bearing surface 30 and the end of the yoke portion layer43 was 0.2 μm, 0.4 μm, 0.6 μm, 0.8 μm, 1.0 μm, and 1.2 μm, respectively.The MR height was 0.6 μm.

In the experiment the following procedure was performed for each of thethin-film magnetic heads. First, data was written by the head in a trackof a recording medium. Next, the head was moved to a neighboring trackwhere data was written 200 times. The head was then moved back to thetrack where the data had been first written. In this track the data wasread and the reproducing output was obtained. The current supplied tothe recording head when writing was performed was 50 mA. In FIG. 21 thereproducing output is expressed as a percentage of a desired reproducingoutput. A hundred percent means that there is no side erase. The smallerthe reproducing output, the greater is the degree of side erase.

As shown in FIG. 21, it is noted that the reproducing output increaseswith an increase in the distance between the air bearing surface 30 andthe end of the yoke portion layer 43. As a result, side erase isprevented more effectively. In addition, it is noted that almost no sideerase occurs when the distance between the air bearing surface 30 andthe end of the yoke portion layer 43 is equal to or greater than 0.6 μm,that is, the MR height. Both side erase and side write result from amagnetic flux leaking from the yoke portion layer 43, following the sameprinciple. Therefore, the foregoing description similarly applies to thecase of side write.

As thus described, it is possible to prevent side write and side erasemore effectively when the distance between the air bearing surface 30and the end of the yoke portion layer 43 facing toward the air bearingsurface 30 is equal to or greater than the MR height.

According to the embodiment, the insulating film 33 made of an inorganicmaterial is provided between the first layer 31 and the second layer 34of the thin-film coil, in addition to the recording gap layer 12. Highinsulation strength is thereby obtained between the first layer 31 andthe second layer 34 of the coil. In addition, it is possible to reduceflux leakage from the layers 31 and 34 of the coil.

The remainder of the configuration, functions and effects of theembodiment are similar to those of the first embodiment.

[Seventh Embodiment]

Reference is now made to FIG. 22 to describe a thin-film magnetic headand a method of manufacturing the same of a seventh embodiment of theinvention. FIG. 22 is a top view of the main part of the thin-filmmagnetic head of the embodiment, wherein an overcoat layer and the otherinsulating layers and films are omitted.

In the seventh embodiment the second portion 8 b of the bottom polelayer 8 has a shape in which a portion closest to the air bearingsurface 30 is smaller than the other portion in width. The width of thisportion decreases toward the air bearing surface 30. An end of thesecond portion 8 b opposite to the air bearing surface 30 has the shapeof a straight line parallel to the air bearing surface 30, and islocated at zero throat height position TH0.

According to the embodiment, since the second portion 8 b has thegeometry as described above, it is possible to reduce the width of thesecond portion 8 b in the air bearing surface 30 and to prevent anincrease in effective track width. In addition, the width of the secondportion 8 b gradually decreases toward the air bearing surface 30. It isthereby possible to prevent a magnetic flux from saturating in thebottom pole layer 8. Furthermore, it is possible to precisely controlthe throat height and the zero throat height position since the end ofthe second portion 8 b opposite to the air bearing surface 30 has theshape of a straight line parallel to the air bearing surface 30.

The remainder of the configuration, functions and effects of theembodiment are similar to those of the sixth embodiment.

The present invention is not limited to the foregoing embodiments butmay be practiced in still other ways. In the foregoing embodiments, forexample, the thin-film magnetic head is disclosed, comprising the MRelement for reading formed on the base body and the induction-typemagnetic transducer for writing stacked on the MR element.Alternatively, the MR element may be stacked on the magnetic transducer.

That is, the induction-type magnetic transducer for writing may beformed on the base body and the MR element for reading may be stacked onthe transducer. Such a structure may be achieved by forming a magneticfilm functioning as the top pole layer of the foregoing embodiments as abottom pole layer on the base body, and forming a magnetic filmfunctioning as the bottom pole layer of the embodiments as a top polelayer facing the bottom pole layer with a recording gap film in between.In this case it is preferred that the top pole layer of theinduction-type magnetic transducer functions as the bottom shield layerof the MR element, too.

According to the first thin-film magnetic head or the first method ofthe invention thus described, the throat height is defined by the secondportion of the first magnetic layer. At least a part of the thin-filmcoil is located on a side of the second portion of the first magneticlayer. The track width is defined by the second magnetic layer. As aresult, the second magnetic layer is formed on the flat surface withaccuracy. It is thereby possible to precisely control the track width aswell as to prevent saturation of a magnetic flux in the second magneticlayer. According to the invention, an end of at least a part of thethin-film coil is located near an end of the second portion of the firstmagnetic layer. It is thereby possible to reduce the yoke length.According to the invention, the portion of the second portion of thefirst magnetic layer that defines the throat height has the lengthbetween an end thereof located in the medium facing surface and theother end, the length being greater than the length of themagnetoresistive element between an end thereof located in the mediumfacing surface and the other end. As a result, it is possible to preventsaturation of a magnetic flux in the first magnetic layer. Since theinvention has the foregoing features, it is possible to preciselycontrol the track width and to prevent a magnetic flux from saturatinghalfway through the magnetic path even when the track width of therecording head is reduced. In addition, a reduction in yoke length isachieved.

According to the first thin-film magnetic head or the first method ofthe invention, a width of the second magnetic layer measured in aposition corresponding to the other end of the portion of the secondportion of the first magnetic layer may be greater than a width of thesecond magnetic layer measured in the medium facing surface. In thiscase, it is possible to prevent a magnetic flux from saturating in thesecond magnetic layer, in particular.

According to the first thin-film magnetic head or the first method ofthe invention, the second magnetic layer may include: a portion having awidth equal to the track width and located closer to the medium facingsurface than the other portion of the second magnetic layer; and theother portion having a width greater than the track width, the width ofthe other portion decreasing toward the medium facing surface. In thiscase, in particular, it is impossible that the cross-sectional area ofthe magnetic path in the second magnetic layer abruptly decreases. It istherefore possible to prevent a magnetic flux from saturating halfwaythrough the magnetic path.

According to the first thin-film magnetic head or the first method, aninsulating layer may be further provided. The insulating layer coversthe at least part of the thin-film coil located on the side of thesecond portion of the first magnetic layer. A surface of the insulatinglayer facing toward the second magnetic layer is flattened together witha surface of the second portion facing toward the second magnetic layer.In this case, in particular, the second magnetic layer is formed on theflat surface with accuracy.

According to the first thin-film magnetic head or the first method, thesecond magnetic layer may include the pole portion layer and the yokeportion layer forming the yoke portion. In addition, an end face of theyoke portion layer facing toward the medium facing surface may belocated at a distance from the medium facing surface. In this case, itis possible to prevent writing of data in a region where data is notsupposed to be written and erasing of data where data is not supposed tobe written.

According to the first thin-film magnetic head or the first method, thepole portion layer may have a length between an end thereof located inthe medium facing surface and the other end, the length being greaterthan the length of the magnetoresistive element between the end thereoflocated in the medium facing surface and the other end. In addition, thedistance between the medium facing surface and the end face of the yokeportion layer facing toward the medium facing surface may be equal to orgreater than the length of the magnetoresistive element. In this case,it is possible to more effectively prevent writing of data in a regionwhere data is not supposed to be written and erasing of data where datais not supposed to be written.

According to the first thin-film magnetic head or the first method, thethin-film coil may include: the first layer located on a side of thesecond portion of the first magnetic layer; and the second layer locatedon a side of the pole portion layer of the second magnetic layer. Inaddition, the first insulating layer and the second insulating layer maybe further provided. The first insulating layer covers the first layerof the coil and has a surface facing toward the second magnetic layer,the surface being flattened together with a surface of the secondportion of the first magnetic layer facing toward the second magneticlayer. The second insulating layer covers the second layer of the coiland has a surface facing toward the yoke portion layer, the surfacebeing flattened together with a surface of the pole portion layer of thesecond magnetic layer facing toward the yoke portion layer. In thiscase, it is possible to form the yoke portion layer of the secondmagnetic layer with accuracy.

According to the first thin-film magnetic head or the first method, theend of the portion of the second portion of the first magnetic layerthat defines the throat height, the end being opposite to the mediumfacing surface, may have a shape of a straight line parallel to themedium facing surface. In this case, it is possible to define the throatheight with more accuracy.

According to the first thin-film magnetic head or the first method, thesecond portion of the first magnetic layer may include a portion locatedcloser to the medium facing surface than the other part of the secondportion, the portion having a width smaller than a width of the otherpart of the second portion. In this case, it is possible to prevent anincrease in effective track width.

According to the first thin-film magnetic head or the first method, thesecond portion of the first magnetic layer may include: the centerportion facing the second magnetic layer and defining the throat height;and the side portions formed at both ends of a width of the centerportion. At least a part of the side portions has a length between anend thereof located in the medium facing surface and the other end, thelength being greater than the throat height. In this case, it ispossible to prevent a magnetic flux from saturating in the portionconnecting the first and second portions of the first magnetic layer toeach other even when the throat height is low.

According to the second thin-film magnetic head or the second method ofthe invention, the second magnetic layer is divided into the poleportion layer and the yoke portion layer. It is thereby possible toprecisely control the track width even when the track width of therecording head is reduced. According to the invention, the pole portionlayer has the length between an end thereof located in the medium facingsurface and the other end, the length being greater than the length ofthe magnetoresistive element between an end thereof located in themedium facing surface and the other end. An end face of the yoke portionlayer facing toward the medium facing surface is located at a distancefrom the medium facing surface, the distance between the medium facingsurface and the end face of the yoke portion layer being equal to orgreater than the length of the magnetoresistive element. As a result, itis possible to prevent a magnetic flux from saturating halfway throughthe magnetic path and to prevent writing of data in a region where datais not supposed to be written and erasing of data where data is notsupposed to be written.

According to the second thin-film magnetic head or the second method ofthe invention, the first magnetic layer may include: the first portionlocated in a region facing toward the at least part of the thin-filmcoil, and the second portion connected to a surface of the first portionfacing toward the thin-film coil, the second portion including a portionthat forms one of the pole portions and defines a throat height. Inaddition, the at least part of the thin-film coil may be located on aside of the second portion of the first magnetic layer. In this case, anend of the at least part of the coil is located near an end of thesecond portion of the first magnetic layer. It is thereby possible toreduce the yoke length.

According to the second thin-film magnetic head or the second method,the thin-film coil may include: the first layer located on a side of thesecond portion of the first magnetic layer; and the second layer locatedon a side of the pole portion layer of the second magnetic layer. Inaddition, the first insulating layer and the second insulating layer maybe further provided. The first insulating layer covers the first layerof the coil and has a surface facing toward the second magnetic layer,the surface being flattened together with a surface of the secondportion of the first magnetic layer facing toward the second magneticlayer. The second insulating layer covers the second layer of the coiland has a surface facing toward the yoke portion layer, the surfacebeing flattened together with a surface of the pole portion layer of thesecond magnetic layer facing toward the yoke portion layer. In thiscase, it is possible to form the yoke portion layer of the secondmagnetic layer with more accuracy.

Obviously many modifications and variations of the present invention arepossible in the light of the above teachings. It is therefore to beunderstood that within the scope of the appended claims the inventionmay be practiced otherwise than as specifically described.

1. A thin-film magnetic head comprising: a medium facing surface thatfaces toward a recording medium; a reproducing head including: amagnetoresistive element; and a first shield layer and a second shieldlayer for shielding the magnetoresistive element, portions of the shieldlayers located on a side of the medium facing surface being opposed toeach other with the magnetoresistive element in between; and a recordinghead including: a first magnetic layer and a second magnetic layermagnetically coupled to each other and including magnetic pole portionsopposed to each other and placed in regions of the magnetic layers on aside of the medium facing surface, each of the magnetic layers includingat least one layer; a gap layer provided between the pole portion of thefirst magnetic layer and the pole portion of the second magnetic layer;and a thin-film coil at least a part of which is placed between thefirst and second magnetic layers, the at least part of the coil beinginsulated from the first and second magnetic layers, wherein: the firstmagnetic layer includes: a first portion located in a region facingtoward the at least part of the thin-film coil; and a second portionincluding the pole portion of the first magnetic layer and connected toa surface of the first portion facing toward the thin-film coil; thesecond portion further includes: a center portion that defines a throatheight; and side portions formed at both ends of a width of the centerportion, the side portions each having a length between an end thereoflocated in the medium facing surface and the other end, the length beinggreater than a length of the center portion between an end thereoflocated in the medium facing surface and the other end; the length ofthe center portion between the end thereof located in the medium facingsurface and the other end is greater than a length of themagnetoresistive element between an end thereof located in the mediumfacing surface and the other end; the at least part of the thin-filmcoil is located on a side of the second portion of the first magneticlayer; and the second magnetic layer defines a track width.
 2. Thethin-film magnetic head according to claim 1, wherein a width of thesecond magnetic layer measured in a position corresponding to the otherend of the center portion is greater than a width of the second magneticlayer measured in the medium facing surface.
 3. The thin-film magnetichead according to claim 2, wherein the second magnetic layer includes: aportion having a width equal to the track width and located closer tothe medium facing surface than the other portion of the second magneticlayer; and the other portion having a width greater than the trackwidth, the width of the other portion decreasing toward the mediumfacing surface.
 4. The thin-film magnetic head according to claim 1,wherein the length of the center portion between the end thereof locatedin the medium facing surface and the other end is 150 to 600 percent ofthe length of the magnetoresistive element between the end thereoflocated in the medium facing surface and the other end.
 5. The thin-filmmagnetic head according to claim 1, wherein the length of the centerportion between the end thereof located in the medium facing surface andthe other end is 300 to 500 percent of the length of themagnetoresistive element between the end thereof located in the mediumfacing surface and the other end.
 6. The thin-film magnetic headaccording to claim 1, further comprising an insulating layer that coversthe at least part of the thin-film coil located on the side of thesecond portion of the first magnetic layer, wherein a surface of theinsulating layer facing toward the second magnetic layer is flattenedtogether with a surface of the second portion facing toward the secondmagnetic layer.
 7. The thin-film magnetic head according to claim 1,wherein the second magnetic layer is made up of one layer.
 8. Thethin-film magnetic head according to claim 1, wherein the secondmagnetic layer includes: a pole portion layer including the pole portionof the second magnetic layer, the pole portion defining the track width;and a yoke portion layer forming a yoke portion and connected to thepole portion layer.
 9. The thin-film magnetic head according to claim 8,wherein an end face of the yoke portion layer facing toward the mediumfacing surface is located at a distance from the medium facing surface.10. The thin-film magnetic head according to claim 9, wherein: the poleportion layer has a length between an end thereof located in the mediumfacing surface and the other end, the length being greater than thelength of the magnetoresistive element between the end thereof locatedin the medium facing surface and the other end; and the distance betweenthe medium facing surface and the end face of the yoke portion layerfacing toward the medium facing surface is equal to or greater than thelength of the magnetoresistive element.
 11. The thin-film magnetic headaccording to claim 8, wherein the thin-film coil includes: a first layerlocated on a side of the second portion of the first magnetic layer; anda second layer located on a side of the pole portion layer of the secondmagnetic layer.
 12. The thin-film magnetic head according to claim 11,further comprising: a first insulating layer that covers the first layerof the coil and has a surface facing toward the second magnetic layer,the surface being flattened together with a surface of the secondportion of the first magnetic layer facing toward the second magneticlayer; and a second insulating layer that covers the second layer of thecoil and has a surface facing toward the yoke portion layer, the surfacebeing flattened together with a surface of the pole portion layer of thesecond magnetic layer facing toward the yoke portion layer.
 13. Thethin-film magnetic head according to claim 1, wherein the other end ofthe center portion has a shape of a straight line parallel to the mediumfacing surface.
 14. The thin-film magnetic head according to claim 1,wherein the second portion of the first magnetic layer surrounds the atleast part of the thin-film coil.
 15. A method of manufacturing athin-film magnetic head comprising: a medium facing surface that facestoward a recording medium; a reproducing head including: amagnetoresistive element; and a first shield layer and a second shieldlayer for shielding the magnetoresistive element, portions of the shieldlayers located on a side of the medium facing surface being opposed toeach other with the magnetoresistive element in between; and a recordinghead including: a first magnetic layer and a second magnetic layermagnetically coupled to each other and including magnetic pole portionsopposed to each other and placed in regions of the magnetic layers on aside of the medium facing surface, each of the magnetic layers includingat least one layer; a gap layer provided between the pole portion of thefirst magnetic layer and the pole portion of the second magnetic layer;and a thin-film coil at least a part of which is placed between thefirst and second magnetic layers, the at least part of the coil beinginsulated from the first and second magnetic layers, wherein the secondmagnetic layer defines a track width, the method including the steps of:forming the reproducing head; forming the first magnetic layer; formingthe gap layer on the first magnetic layer; forming the second magneticlayer on the gap layer; and forming the thin-film coil such that the atleast part of the coil is placed between the first and second magneticlayers, the at least part of the coil being insulated from the first andsecond magnetic layers, wherein: the step of forming the first magneticlayer includes formation of: a first portion located in a region facingtoward the at least part of the thin-film coil; and a second portionincluding the pole portion of the first magnetic layer and connected toa surface of the first portion facing toward the thin-film coil; thesecond portion is formed to further include: a center portion thatdefines a throat height; and side portions formed at both ends of awidth of the center portion, the side portions each having a lengthbetween an end thereof located in the medium facing surface and theother end, the length being greater than a length of the center portionbetween an end thereof located in the medium facing surface and theother end; the length of the center portion between the end thereoflocated in the medium facing surface and the other end is made greaterthan a length of the magnetoresistive element between an end thereoflocated in the medium facing surface and the other end in the step offorming the first magnetic layer; and the at least part of the thin-filmcoil is located on a side of the second portion of the first magneticlayer in the step of forming the coil.
 16. The method according to claim15, wherein, in the step of forming the second magnetic layer, a widthof the second magnetic layer measured in a position corresponding to theother end of the center portion is made greater than a width of thesecond magnetic layer measured in the medium facing surface.
 17. Themethod according to claim 16, wherein the step of forming the secondmagnetic layer includes formation of: a portion having a width equal tothe track width and located closer to the medium facing surface than theother portion of the second magnetic layer; and the other portion havinga width greater than the track width, the width of the other portiondecreasing toward the medium facing surface.
 18. The method according toclaim 15, wherein, in the step of forming the first magnetic layer, thelength of the center portion between the end thereof located in themedium facing surface and the other end is made to be 150 to 600 percentof the length of the magnetoresistive element between the end thereoflocated in the medium facing surface and the other end.
 19. The methodaccording to claim 15, wherein, in the step of forming the firstmagnetic layer, the length of the center portion between the end thereoflocated in the medium facing surface and the other end is made to be 300to 500 percent of the length of the magnetoresistive element between theend thereof located in the medium facing surface and the other end. 20.The method according to claim 15, further including the step of formingan insulating layer that covers the at least part of the thin-film coillocated on the side of the second portion of the first magnetic layer,wherein a surface of the insulating layer facing toward the secondmagnetic layer is flattened together with a surface of the secondportion facing toward the second magnetic layer.
 21. The methodaccording to claim 15, wherein the second magnetic layer is made up ofone layer.
 22. The method according to claim 15, wherein the step offorming the second magnetic layer includes formation of: a pole portionlayer including the pole portion of the second magnetic layer, the poleportion defining the track width; and a yoke portion layer forming ayoke portion and connected to the pole portion layer.
 23. The methodaccording to claim 22, wherein, in the step of forming the secondmagnetic layer, an end face of the yoke portion layer facing toward themedium facing surface is located at a distance from the medium facingsurface.
 24. The method according to claim 23, wherein, in the step offorming the second magnetic layer, the pole portion layer is made tohave a length between an end thereof located in the medium facingsurface and the other end, the length being greater than the length ofthe magnetoresistive element between the end thereof located in themedium facing surface and the other end; and the distance between themedium facing surface and the end face of the yoke portion layer facingtoward the medium facing surface is made equal to or greater than thelength of the magnetoresistive element.
 25. The method according toclaim 22, wherein the step of forming the thin-film coil includesformation of: a first layer located on a side of the second portion ofthe first magnetic layer; and a second layer located on a side of thepole portion layer of the second magnetic layer.
 26. The methodaccording to claim 25, further including the steps of: forming a firstinsulating layer that covers the first layer of the coil and has asurface facing toward the second magnetic layer, the surface beingflattened together with a surface of the second portion of the firstmagnetic layer facing toward the second magnetic layer; and forming asecond insulating layer that covers the second layer of the coil and hasa surface facing toward the yoke portion layer, the surface beingflattened together with a surface of the pole portion layer of thesecond magnetic layer facing toward the yoke portion layer.
 27. Themethod according to claim 15, wherein, in the step of forming the firstmagnetic layer, the other end of the center portion is made to have ashape of a straight line parallel to the medium facing surface.
 28. Themethod according to claim 15, wherein the second portion of the firstmagnetic layer is formed to surround the at least part of the thin-filmcoil in the step of forming the first magnetic layer.